1. Field of the Invention
This invention relates to a plasma display panel, and more particularly to a plasma display panel that is capable of improving its discharge efficiency and brightness.
2. Description of the Related Art
Generally, a plasma display panel (PDP) radiates a fluorescent body by an ultraviolet ray generated during a gas discharge to thereby display a picture including characters and graphics. Such a PDP is easy to be made into a thin-film and large-dimension type. Moreover, the PDP provides a very improved picture quality owing to a recent technical development.
Referring to FIG. 1, a conventional three-electrode, AC surface-discharge PDP includes a scanning electrode Y and a sustaining electrode Z provided on an upper substrate 10, and a data electrode X provided on a lower substrate 18.
The scanning electrode Y and the sustaining electrode Z have transparent electrodes 12Y and 12Z with a large width and metal bus electrodes 13Y and 13Z with a small width, respectively, and are formed on the upper substrate in parallel. An upper dielectric layer 14 and a protective film 16 are disposed on the upper substrate 10 in such a manner to cover the scanning electrode Y and the sustaining electrode Z. Wall charges generated upon plasma discharge are accumulated in the upper dielectric layer 14. The protective film 16 prevents a damage of the upper dielectric layer 14 caused by a sputtering during the plasma discharge and improves the emission efficiency of secondary electrons. This protective film 16 is usually made from magnesium oxide (MgO). The data electrode X Is perpendicular to the scanning electrode Y and the sustaining electrode Z.
A lower dielectric layer 22 and barrier ribs 24 are formed on the lower substrate 18. The surfaces of the lower dielectric layer 22 and the barrier ribs 24 are coated with a fluorescent material layer 26. The barrier ribs 24 separate adjacent discharge spaces in the horizontal direction to thereby prevent optical and electrical crosstalk between adjacent discharge cells. The fluorescent layer 26 is excited by an ultraviolet ray generated during the plasma discharge to generate any one of red, green and blue visible light rays. An inactive mixture gas of He+Xe, Ne+Xe or He+Xe+Ne is injected into a discharge space defined between the upper and lower substrate 10 and 18 and the barrier rib 24.
Discharge cells of such a PDP are arranged at a panel 30 in a matrix pattern as shown in FIG. 2. The scanning electrodes Y1 to Ym and the sustaining electrodes Z1 to Zm arranged in parallel cross the data electrodes X1 to Xn at each discharge cell.
Such a PDP drives one frame, which is divided into various sub-fields having a different discharge frequency, so as to realize gray levels of a picture. Each sub-field is again divided into a reset interval for uniformly causing a discharge, an address interval for selecting the discharge cell and a sustaining interval for realizing the gray levels depending on the discharge frequency.
For instance, when it is intended to display a picture of 256 gray levels, a frame interval equal to {fraction (1/60)} second (i.e. 16.67 msec) is divided into 8 sub-fields SF1 to SF8 as shown in FIG. 3. Each of the 8 sub-fields SF1 to SF8 is again divided into a reset interval, an address interval and a sustaining interval. The reset interval and the address interval of each sub-field are equal every sub-field. The address discharge for selecting the cell is caused by a voltage difference between the data electrode X and the scanning electrode Y. The sustaining interval is increased at a ration of 2n (wherein n=0, 1, 2, 3, 4, 5, 6 and 7) at each sub-field. A sustaining discharge frequency in the sustaining interval is controlled at each sub-field in this manner, to thereby realize a gray scale required for a picture display. The sustaining discharge is generated by a high voltage of pulse signal applied alternately to the scanning electrode Y and a sustaining electrode z. FIG. 4 illustrates driving waveforms: the three-electrode PDP.
Referring to FIG. 4, in the reset interval, signals of square wave or ramp wave type (not shown) are supplied at least once to the sustaining electrode Z or the scanning electrodes Y1 to Ym to simultaneously discharge the discharge cells of the entire screen. Uniform wall charges are accumulated within the cells of the entire screen by the discharge during the reset interval.
In the address interval, a scanning pulse Sp with a negative polarity is sequentially applied to the scanning electrodes Y1 to Ym and a data pulse Vd synchronized with the scanning pulse Sp is applied to the data electrode X. An address discharge is generated at the discharge cell supplied with the data pulse Vd.
In the sustaining interval, a sustaining pulse Vs are alternately applied to the scanning electrode Y and the sustaining electrode Z. Then, the discharge calls selected by the address discharge generates a sustaining discharge continuously whenever the sustaining pulse Vs is applied.
Since such a three-electrode FDP has the scanning electrode Y and the sustaining electrode Z positioned at the upper center of the discharge space, it has a low utility of the discharge space. For this reason, in the three-electrode PDP, a voltage for causing a sustaining discharge and a power consumption are high while discharge and light-emission efficiencies daring the sustaining discharge are low. More specifically, the sustaining discharge takes a surface discharge between the scanning electrode Y and the sustaining electrode Z. However, since the scanning electrode Y and the sustaining electrode Z concentrate at the center of the cell to lower a discharge-initiating voltage, a discharge path becomes short to cause low discharge and light-emission efficiencies. When a distance between the scanning electrode Y and the sustaining electrode is enlarged so as to enhance the efficiencies, a discharge-initiating voltage becomes high in proportional to a distance between the two electrodes.
In order to solve the problems of the three-electrode PDP, there has been suggested a five-electrode PDP in which an electrode for causing a sustaining discharge is divided into four electrodes,
Referring to FIG. 5, the conventional five-electrode PDP includes a pair of trigger electrodes TY and TZ provided on an upper substrate 34 in such a manner to be positioned at the center of a discharge cell, a pair of sustaining electrodes SY and SZ provided on the upper substrate 34 in such a manner to have the pair of trigger electrodes TY and TZ therebetween and to be positioned at the edge of the discharge cell, and a data electrode X provided at a lower substrate 40 in such a manner to be perpendicular to the trigger electrodes TY and TZ and the sustaining electrodes SY and SZ.
The pair of trigger electrodes TY and TZ and the pair or sustaining electrodes SY and SZ include transparent electrodes having a large width and metal bus electrodes having a small width, respectively, and are formed on the upper substrate 34 in parallel. The pair of trigger electrodes TY and TZ are set to have a small distance Ni between the electrodes.
The pair of sustaining electrodes SY and SZ are set to have a large distance Wi between the electrodes. The pair of sustaining electrodes SY and SZ causes a long-path discharge by utilizing space charges and wall charges formed by a discharge between the pair of trigger electrodes TY and TZ.
An upper dielectric layer 36 and a protective film 38 are disposed on the upper substrate 34 in such a manner to cover the pair of trigger electrodes TY and TZ and the pair of sustaining electrodes SY and SZ, Wall charges generated upon plasma discharge are accumulated in the upper dielectric layer 36. The protective Film 38 prevents a damage of the upper dielectric layer 36 caused by a sputtering during the plasma discharge and improves the emission efficiency of secondary electrons. This protective film 38 is usually made from magnesium oxide (MgO).
A lower dielectric layer 44 and barrier ribs 46 are formed on the lower substrate 40. The surfaces of the lower dielectric layer 44 and the barrier ribs 46 are coated with a fluorescent material layer 48. The barrier ribs 46 separate adjacent discharge spaces in the horizontal direction to thereby prevent optical and electrical crosstalk between adjacent discharge cells. The fluorescent material layer 48 is excited by an ultraviolet ray generated during the plasma discharge to generate any one of red, green and blue visible light rays. An inactive mixture gas of He+Xe, Ne+Xe or He+Xe+Ne is injected into a discharge space defined among the upper and lower substrate 34 and 40 and the barrier ribs 46.
Discharge cells of such a five-electrode PDP are arranged at a panel 5O in a matrix pattern as shown in FIG. 6.
Like the three-electrode PDP, the five-electrode AC surface-discharge PDP drives one frame, which is divided into various sub-fields each of which includes a reset interval, an address interval and a sustaining interval and has a different discharge frequency, so as to realize gray levels of a picture.
During the reset interval, the discharge cells of the entire screen is initialized. During the address interval, the scan pulse and the data pulse are supplied to the first trigger electrode TY and the data electrode X respectively, and then the address discharge is caused between the first trigger electrode TY and the data electrode X such that a cell is selected. During the sustaining interval, pulses are alternately applied to each electrode of the pair of trigger electrodes TY and TZ, and at the same time, pulses are alternately applied to each electrode of the pair of sustaining electrodes Sy and Sz. At this moment, the trigger discharge between the pair of trigger electrodes TY and TZ occurs first, then a long path discharge occurs between the pair of sustaining electrodes SY and SZ by using the priming charged particles generated by the trigger discharge.
In the five-electrode PDP, it is necessary that a high sustaining voltage is applied to the pair of sustaining electrodes SY and SZ for effectively causing the long path discharge, i.e., the sustaining discharge. By the way, there can occurs a discharge between the data electrode X that sustains the ground level GND in the sustaining interval and at least one of the pair of sustaining electrodes SY and SZ when too high a voltage is applied to the pair of sustaining electrodes SY and SZ. In this case, the discharge path is dispersed to decrease the efficiency of the sustaining discharge, thereby deteriorating brightness.
Also, in the five-electrode PDP, it is desirable that a short path discharge between the pair of trigger electrodes TY and TZ should occur as small as possible for increasing the efficiency and brightness of the long path discharge between the pair of the sustaining electrodes SY and SZ. And yet, because a let of wall charges are formed on the first trigger electrode TY by the address discharge and the gap between the pair of trigger electrodes TY and TZ, it is likely that the short path discharge occurs intensely between the pair of trigger electrodes TV and TZ.
Accordingly, it is an object of the present invention to provide a plasma display panel that is capable of improving its discharge efficiency and brightness.
In order to achieve these and other objects of the invention, a plasma display panel according to one aspect of the present invention includes an upper electrode group formed on an upper substrate, including a scanning electrode to which a scanning voltage is supplied; barrier ribs formed on a lower substrate facing the upper substrate with a discharge space therebetween for dividing the discharge space; and an address electrode formed on the lower substrate to be located under the barrier ribs, and to which a data voltage is supplied.
The plasma display panel further includes an auxiliary address electrode extended from one side of the address electrode to the direction of the scanning electrode.
In the plasma display panel, the auxiliary address electrode overlaps with the scanning electrode and has the discharge space therebetween.
In the plasma display panel, a cell is selected by a discharge between the scanning electrode and the auxiliary address electrode of the address electrode.
In the plasma display panel, the upper electrode group includes a pair of trigger electrodes; and a pair of sustaining electrodes that has a wider gap therebetween than the pair of trigger electrodes and has the pair of trigger electrodes arranged therebetween.
A plasma display panel according to another aspect or the present invention includes an upper electrode group formed on an upper substrate, including a scanning electrode to which a scanning voltage is supplied; an address electrode formed on a lower substrate facing the upper substrate with a discharge space therebetween to cross with the upper electrode group perpendicularly; barrier ribs formed on the lower substrate for dividing the discharge space, and an auxiliary barrier rib extending toward the discharge space from at least one side of the barrier ribs.
In the plasma display panel, the auxiliary barrier ribs are respectively extended from both sides of the barrier ribs and are opposite to each other.
In the plasma display panel, the upper electrode group includes a pair of trigger electrodes; and a pair of sustaining electrodes that has a wider gap therebetween than the pair of trigger electrodes and has the pair of trigger electrodes arranged therebetween.
In the plasma display panel, the auxiliary barrier rib has the discharge space therebetween and overlaps with the pair of trigger electrodes.
In the plasma display panel, the auxiliary barrier rib overlaps with other electrode than the electrode to which a scanning voltage is supplied out of the pair of trigger electrodes, having a discharge space therebetween.
In the plasma display panel, the auxiliary barrier rib is extended to the direction of the width of the barrier ribs.
A plasma display panel according to another aspect of the present invention includes an upper electrode group formed on an upper substrate, including a scanning electrode to which a scanning voltage is supplied; and an address electrode formed on a lower substrate facing the upper substrate with a discharge space therebetween to cross with the upper electrode group perpendicularly, and wherein the width of at least one outer electrode that is located at the outer side among the upper electrode group is set to be wider than that of at, least one inner electrode that is located between the outer electrodes.
In the plasma display panel, the outer electrodes includes a first sustaining electrode to which the scanning electrode is supplied; and a second sustaining electrode separated from the first sustaining electrode with at least one inner electrode therebetween.
In the plasma display panel, the electrode width of the first and the second sustaining electrodes is set to be wider than that of at least one of the inner electrodes.
In the plasma display panel, the electrode width of the first sustaining electrode is set to be wider than that of at least one of the inner electrodes.
In the plasma display panel, the electrode width of the second sustaining electrode is set to be equal to that of at least one of the inner electrodes.
The plasma display panel further includes a dielectric layer formed on the upper substrate to cover the upper electrode group; a protective film deposited on the dielectric layer; barrier ribs formed on the lower substrate for dividing the discharge space; and a fluorescent material layer formed on the surface of the barrier ribs and the lower substrate.